The X100B series tube amps were a mainstay on many arena stages and MTV videos throughout the 1980's and 90's. Artists such as Frank Zappa, Craig Chaquico with Jefferson Starship, Warrant, Warren Cuccurullo with Missing Persons, and Steve Vai all played X100B amps. Frank Zappa raved about the Clean channel on this amp. Steve Vai recorded a song called "Blue Powder" (available on his first solo release Flexable) featuring the X100B. The release of Series IV includes a master volume switchable to boost mode and a 4 button optional footswitch with LED indicators (Channel, Effects, Reverb, Boost). As a tribute to the original X100B amps, the new Series IV is badged with the vintage Carvin logo.